Cook the jumbo pasta shells according to the package instructions until al dente. Drain and set aside.
In a mixing bowl, combine the shredded chicken, pesto, ricotta cheese, 1/2 cup of mozzarella cheese, garlic powder, salt, and pepper. Mix until well blended.
Spread a thin layer of marinara sauce in the bottom of a 9x13 inch baking dish.
Using a spoon, carefully stuff each cooked pasta shell with the chicken and pesto mixture, placing them in the prepared baking dish.
Once all shells are filled, pour the remaining marinara sauce evenly over the stuffed shells. Top with the remaining mozzarella and the grated Parmesan cheese.
Cover the dish with aluminum foil and bake for 25 minutes. Then, remove the foil and bake for an additional 10-15 minutes until the cheese is bubbly and golden.
Remove from the oven and let it cool for a few minutes before serving.
Garnish with fresh basil leaves for a pop of color and freshness.
Notes
Let the dish cool for a few minutes before serving for better flavor.